Hot water in toilet

[HalM]

Hi,
I help out with maintenance in a seniors retirement building (13 year old building).
Over the past couple of months one unit on the 5th floor reports having hot water in the toilet from about 2 a.m. to 7 a.m. She notices it during the night when she gets up to go to the bathroom and then it usually is back to normal after about 8 a.m. While this happens hot water also comes out of the cold water taps in the bathroom and kitchen faucets. No other units have reported this issue happening. It has been happening intermittently over the past 2 to 3 months.

I'm just looking for ideas on what to look for and where to focus my attention, what questions to ask, etc?

Thanks,
Hal

 

[GrumpyPlumber]

There's obviously a cross connection, might be through a one piece faucet or a laundry valve nearby.

 

[Sponsor]

 

[Neil Binda]

There's obviously a cross connection, might be through a one piece faucet or a laundry valve nearby.

It's most likely a stuck check valve stuck open or closed in their shower .

Do they have a thermostatic mixer ?

 

[Reach4]

Less likely, but there is a type of hot water recirculation that uses the cold water line as a return. Those would typically have a device in the cabinet under the lavatory.

 

[HalM]

It's most likely a stuck check valve stuck open or closed in their shower .

Do they have a thermostatic mixer ?

Yes, there is a mixing valve in each of these units.

 

[Neil Binda]

Yes, there is a mixing valve in each of these units.

That is the issue you have .

Do you have a picture of the shower valve?

You would have to change the check valves in the shower mixer . As long as you have isolated the issue to that unit you should be fine .

 

[Norcal01]

Is there a janitors closet nearby that the hot and cold water is left on & turned off at the spout? Until I got people to turn off the faucets would have problems with water temps, there are hoses supplying chemical mixing stations & they left the valves open, allowing the hot & cold to mix, plus always worried about a hose rupture during off hours making a huge mess.